Case Study 14-2 A health educator wants to evaluate the effect of a dental film on the frequency with which children brush their teeth. A random selection of 8 children are used for the experiment. First, a baseline of the number of times the children brush their teeth over a month's period is established. Next, the children are shown the dental film and again the number of teeth brushings are recorded for a month. The following data are recorded.

Subject 1 2 3 4 5 6 7 8
After film 28 29 25 30 25 27 28 24
Baseline 25 28 22 30 26 24 25 22

14. Refer to Case Study 14-2. The obtained value of the appropriate statistic is .
a. -3.13
b. 3.14
c. 3.58
d. 3.57

15. Refer to Case Study 14-2. The df for determining tcrit equal .
a. 8
b. 16
c. 7
d. 14

16. Refer to Case Study 14-2. Using  = .052 tail, tcrit = .
a. +2.365
b. ±2.365
c. ±2.145
d. +2.365

17. Refer to Case Study 14-2. Using  = 0.052 tail, what do you conclude?
a. retain H0; the film has no effect on the frequency of tooth brushing
b. reject H0; the film affects the frequency of tooth brushing
c. accept H0; the film has no effect on the frequency of tooth brushing
d. reject H0; chance alone is a reasonable explanation of the data